This invention relates generally to apparatus for providing heat transfer between two fluids of different temperature separated by a heat conducting barrier or partition and more particularly to a means for providing an increase in the heat transfer efficiency across the partition.
Heat exchangers are well known in the state of the art; however, a principal impediment to effective transfer or transmission of heat from a warm fluid to a cold fluid is the boundary layer of fluid which adheres to each side of the partition or barrier separating the two fluids. Even when the motions of the fluid are fully turbulent, there exists a laminar sub-layer which operates to obstruct the transmission of heat, which obstruction often is greater than that provided by the partition itself. While various methods and types of apparatus have been suggested in the past for overcoming the problem, such as by means of driving the fluid with sonic waves and vibrating the partition with external vibration generators, these measures while being partially effective at best are inherently limited in their ability to generate a motion which is particularly adapted to minimize the thickness of the laminar sub-layer on each side of the partition. The inventor of this invention has previously proposed a solution which is shown and described in U.S. patent application Ser. No. 030,966 filed on Mar. 17, 1979, entitled, "Piezoelectric Polymer Heat Exchanger," wherein there is shown and described a single or unitary flexible sheet of piezoelectric material which is utilized as the barrier or partition between two heat exchanger channels. The flexible piezoelectric sheet there additionally includes a pattern of electrodes to which is applied an alternating current electrical signal having a frequency substantially equal to the natural frequency of the partition, which when applied, causes the sheet to flex at its resonance frequency and in so doing, sets up a standing wave or traveling wave pattern, causing a wave or flipping motion to occur which pushes the sub-laminar layer away from the piezoelectric sheet.
Accordingly, it is an object of the present invention to provide an improvement in apparatus for increasing the efficiency of heat transfer in a fluid heat exchanger.
It is yet another object of the present invention to provide improvement in apparatus for promoting the flow of fluids within a heat exchanger.
Still a further object of the invention is to provide an improvement in the partition or barrier separating the two fluids in a heat exchanger.